From 544a49200066b87cbf5c83336fb573e2fb5256d9 Mon Sep 17 00:00:00 2001
From: eldritch horrors <pennae@lix.systems>
Date: Sun, 10 Mar 2024 21:27:45 +0100
Subject: [PATCH] wip: dependency-tracked build triggering

---
 buildbot_nix/__init__.py | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/buildbot_nix/__init__.py b/buildbot_nix/__init__.py
index a2d8775..371f95b 100644
--- a/buildbot_nix/__init__.py
+++ b/buildbot_nix/__init__.py
@@ -60,11 +60,13 @@ class BuildTrigger(Trigger):
         builds_scheduler: str,
         skipped_builds_scheduler: str,
         jobs: list[dict[str, Any]],
+        drv_info: dict[str, Any],
         **kwargs: Any,
     ) -> None:
         if "name" not in kwargs:
             kwargs["name"] = "trigger"
         self.jobs = jobs
+        self.drv_info = drv_info
         self.config = None
         self.builds_scheduler = builds_scheduler
         self.skipped_builds_scheduler = skipped_builds_scheduler
@@ -87,6 +89,25 @@ class BuildTrigger(Trigger):
         build_props = self.build.getProperties()
         source = f"nix-eval-lix"
 
+        all_deps = dict()
+        for drv, info in self.drv_info.items():
+            all_deps[drv] = set(info.get("inputDrvs").keys())
+        def closure_of(key, deps):
+            r = set()
+            r.add(key)
+            while True:
+                more = set(r)
+                more.update(*( deps[k] for k in r ))
+                if r == more:
+                    break
+                r = more
+            r.remove(key)
+            return r
+        job_set = set(( drv for drv in ( job.get("drvPath") for job in self.jobs ) if drv ))
+        all_deps = { k: list(closure_of(k, all_deps).intersection(job_set)) for k in job_set }
+
+        build_props.setProperty("sched_state", all_deps, source, True)
+
         triggered_schedulers = []
         for job in self.jobs:
             attr = job.get("attr", "eval-error")
@@ -178,6 +199,24 @@ class NixEvalCommand(buildstep.ShellMixin, steps.BuildStep):
                 if not system or system in self.supported_systems:  # report eval errors
                     filtered_jobs.append(job)
 
+            drv_show_log: Log = yield self.getLog("stdio")
+            drv_show_log.addStdout(f"getting derivation infos\n")
+            cmd = yield self.makeRemoteShellCommand(
+                stdioLogName=None,
+                collectStdout=True,
+                command=(
+                    ["nix", "derivation", "show", "--recursive"]
+                    + [ drv for drv in (job.get("drvPath") for job in filtered_jobs) if drv ]
+                ),
+            )
+            yield self.runCommand(cmd)
+            drv_show_log.addStdout(f"done\n")
+            try:
+                drv_info = json.loads(cmd.stdout)
+            except json.JSONDecodeError as e:
+                msg = f"Failed to parse `nix derivation show` output for {cmd.command}"
+                raise BuildbotNixError(msg) from e
+
             self.build.addStepsAfterCurrentStep(
                 [
                     BuildTrigger(
@@ -185,6 +224,7 @@ class NixEvalCommand(buildstep.ShellMixin, steps.BuildStep):
                         skipped_builds_scheduler=f"lix-nix-skipped-build",
                         name="build flake",
                         jobs=filtered_jobs,
+                        drv_info=drv_info,
                     ),
                 ],
             )